You also need to figure out if you want a horse that is gaited or not. Around here most of the horses are gaited and used for nothing but trail riding. I don't have a ton of experience with different breeds, but our TWH's are generally pretty calm and bombproof. I'd also get an idea of what size you're interested in. Both of our horses are on the small side (14.2 and 15 hands) which I think is ideal for trail riding (easier to duck under trees) and they probably eat less than a the 17+ hand horse we looked at first (maybe not, but I'd assume bigger would usually eat more). Plus, we're both short, so smaller is better and less scary for a newbie.
Have you thought about leasing a horse for a while to figure out what you like and don't like? Have you taken lessons on any particular breeds?
Of course we were going to get 2 geldings - between ages 5 and 10. We ended up with 2 mares - ages 3 and 5. We just found two horses that were right for us. My horse, the then 3 year old (way to young for a beginner according to everything I'd read), has turned out to be the calmest and most bombproof horse whenever we trail ride with a group. The horse that should have been all wrong for me, turned out to be perfect. Just look at lots of horses with an open mind and don't jump into anything.